The MoBa cohort study provides a clearer picture of how genes influence our lives

A new study published in Nature shows that family-based genetic data can provide researchers with more precise answers about how genes influence health and development. The study is based on data from more than 44,000 mother–father–child trios in the Norwegian Mother, Father and Child Cohort Study, called MoBa. By combining genetic data from both parents and children, researchers can distinguish between effects attributable to an individual’s own genetics and those arising from other influences.

• Family genetic designs in MoBa provide insights into health and functioning (nature.com)

“MoBa is helping to advance a new generation of studies that use genetic data from both parents and children to understand how genes and environments jointly shape health and development across the life course,” says Alexandra Karoline Havdahl, senior author of the paper and scientific director of MoBa.

Genes and family environments: An intricate connection

Over the past decade, genetic studies have identified thousands of genetic variants linked with human traits, health and disease. Most of these studies rely on genetic data from unrelated individuals. 

Parents’ genetics can shape their children’s outcomes not only through inherited genetic differences, but also through the environments they create. This complexity makes it challenging to determine whether an observed association is due to the individual’s own genetics or aspects of the family environment.

“We need to consider the intricate connections between genes and family environments. By analysing genetic data from both parents and children, we can obtain a clearer picture of how children’s genes and environments influence their health and development,” says Havdahl.

Examining children’s height, educational achievement, sleep and depressive symptoms

The researchers used family data from MoBa to investigate how children’s genetic differences are associated with height, educational achievement, sleep duration and depressive symptoms. They initially conducted traditional analyses in unrelated children to see how the children's genetics are associated with these traits. Subsequently, they integrated genetic data from both children and parents into models that estimate direct genetic effects while controlling for parental genetics.

When the researchers accounted for genetic data from both parents and children, the children’s genes explained a substantially smaller proportion of variation in children’s height and educational achievement than in traditional genetic analyses. The findings suggest that traditional studies of unrelated individuals may overestimate how much variation is explained by an individual’s own genetic differences.

One clear example was educational achievement. Analyses based on children alone suggested that genetic differences explained around 31% of the variation in children’s performance on national tests. However, when the researchers incorporated genetic data from both parents and children, the estimated contribution of the children’s genetics fell to 22%.

The results indicate that part of the genetic findings from studies of unrelated people may be due to family and environmental factors, rather than direct genetic effects.

Why is MoBa important?

Although family data are crucial for distinguishing direct genetic effects from other influences, there are very few large-scale health studies with genetic data from mother-father-child trios. Family data help researchers better understand how genes shape health and development by accounting for influences that do not arise directly from an individual’s own genetic differences.

The Norwegian Mother, Father and Child Cohort Study is especially valuable because it combines extensive genetic data from parents and children with longitudinal follow-up of approximately 100,000 children from fetal life into adulthood. This makes MoBa a unique resource for future research on how genes, family environments and health are connected across the life course.

“MoBa is one of the few population-based studies in the world with genetic data from mothers, fathers and children on such a large scale. This makes MoBa a unique resource for improving public health by increasing our understanding of how genetic, environmental and social factors jointly shape health and development throughout life,” Havdahl concludes.

About the study

The study was led by researchers at the PsychGen Centre of the Norwegian Institute of Public Health and Lovisenberg Diaconal Hospital, in collaboration with researchers from, among others, Oslo University Hospital, the University of Oslo, the University of Bristol and University College London. The analyses are based on genetic data from more than 44,000 mother–father–child trios in the Norwegian Mother, Father and Child Cohort Study (MoBa).

"It is rewarding to see that the long-term collaboration between hospitals and research institutions in MoBa has now led to such groundbreaking findings," says Ole Andreassen, senior author on the article from Oslo University Hospital and the University of Oslo.

The study was published on August 19^th 2026 in the internationally recognised journal Nature.

Limitations and next steps

Within-family genetic analyses are statistically demanding, and even with MoBa’s extensive data resources, the number of complete family trios remains limited. Another limitation is that most participants have genetic ancestry similar to European reference populations, meaning the findings may not be generalisable. The authors therefore emphasise the importance of expanding family-based research by including greater diversity and larger sample sizes.